The technique for selectively epoxidizing one double bond at a specific position of diolefin is of low productivity (low reactivity, low selectivity), and application thereof is often limited to those with structures of some kinds.
Peracids have been conventionally used as selective epoxidizing agents for diolefin (see, for example, Chem. Ber., 1985, 118, 1267-1270). However, in the technique, a large amount of diepoxides are produced as by-products, and equivalent amounts of acids derived from the oxidizing agents are produced, which cause problems such as corrosion of apparatuses.
A selective epoxidizing method of a diolefin using oxone as an oxidizing agent in the presence of a ketone catalyst (for example, see J. Org. Chem., 1998, 63, 2948-2953) has been known. In this reaction, there are problems that a large amount (20 to 30 mol % relative to diolefin) of ketones of catalysts are required, and the reaction conditions such as a pH and a reaction temperature must be strictly controlled in order to prevent reacting oxon from being decomposed.
On the other hand, a hydrogen peroxide solution is cheep, non-corrosive, and environmentally friendly because any by-product is not produced or the by-product is water. It is an excellent oxidizing agent to be used in industry.
As the methods for producing an epoxy compound from an olefin using a hydrogen peroxide solution as an epoxidizing agent, (1) an epoxidizing method with hydrogen peroxide in the presence of quaternary ammonium chloride, phosphoric acids, and a tungsten metal salt {see Kokai (Jpn. Unexamined Patent Publication) 2003-192679 (Patent Publication 1 hereinafter)}; (2) an epoxidizing method with hydrogen peroxide using organic oxorhenium as a catalyst {see Kokai 2001-25665 (Patent Publication 2 hereinafter)}; (3) an epoxidizing method with titanium silicate and hydrogen peroxide (see, for example, Journal of Catalysis, 1993, 140, 71-83); and (4) an epoxidizing method with hydrogen peroxide in the presence of a fluoroalkyl ketone catalyst (see, for example, Chem. Commun., 1999, 263-264) have been known. These methods basically relate to epoxidizing of a monoolefin having sole double bond, and do not indicate selective epoxidizing of diolefin.
With respect to selective epoxidizing of diolefin using a hydrogen peroxide solution as an epoxidizing agent, there are (5) a method for epoxidizing diolefin with hydrogen peroxide in the presence of a catalyst represented by the formula Q3XW4O24 (in the formula, Q represents a quaternary ammonium cation having carbon atoms up to 70, X represents P or As) (see, for example, Kokai 4-275281); (6) a method for epoxidizing diolefin having a methacrylic acid unit with hydrogen peroxide in the presence of quaternary ammonium chloride, phosphoric acid, and a tungsten compound (see, for example, Tetrahedron, 1992, 48 (24), 5099-5110); (7) a method for epoxidizing diolefin with hydrogen peroxide in the presence of a tungsten and molybdenum polyoxometalate complex {see, for example, Kokai 2002-155066 (Patent Publication 3 hereinafter)}; and (8) a method for epoxidizing diolefin using organic oxorhenium as a catalyst (Angew. Chem. Int. Ed. Engl., 1991, 30(12), 1638-1641). However, in the above method (5), the amount of hydrogen peroxide is less than one equivalent amount relative to one equivalent amount of diolefin, the reaction yields are very poor (32 to 48% relative to the used diolefin), it takes much time and it costs much money for performing separation and purification steps which result in poor productivity. As the catalyst has a surfactant property and a halogenated hydrocarbon such as methylene chloride is required for phase separation after the reaction is complete, it is not environmentally friendly. The above methods (6) and (7) have strict substrate specificity, the substrates in the methods (6) and (7) are limited to diolefins having a methacrylic acid unit and large cycle diolefins having 8 to 20 rings, respectively. Especially in the above method (8), substrate conversion ratio of diolefin is very high, but a large amount of a diol compound of a hydrolysis product from a bifunctional epoxy monomer is produced as a by-product, and the yield of the monoepoxy compound is low. Organic oxorhenium is very expensive, and they are industrially cost ineffective.
Accordingly, a method for selectively producing a bifunctional epoxy monomer in high yield at a low cost from diolefin, under a mild condition, without any use of an organic solvent, by easy operation, has been strongly desired.
[Patent Publication 1] Kokai 2003-192679
[Patent Publication 2] Kokai 2001-25665
[Patent Publication 3] Kokai 2002-155066